Self-Aligned Spin Torque Oscillator for Magnetic Recording Head
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Solution Overview
Problem
The challenge in high frequency magnetic field assisted magnetic recording is maintaining accurate positional alignment between the main magnetic pole and the spin torque oscillator (STO) in the cross-track direction, which affects the stability and effectiveness of the high frequency magnetic field assist, leading to variations in recording density and performance.
Innovation Solution
A structure is implemented where a step is formed between the main magnetic pole and the gap material, allowing the STO to be self-aligned by adjusting the film thickness and etching processes, ensuring precise positioning and effective operation of the STO, thereby stabilizing the high frequency magnetic field assist.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the STO is positioned close to the main magnetic pole to enhance the high frequency magnetic field assist effect, then the recording density and assist effect are improved, but the positional alignment accuracy in the cross-track direction deteriorates due to manufacturing variations
Solution Approach 1:
The STO structure is designed to self-align with the main magnetic pole through integrated formation processes. The STO and main magnetic pole are formed simultaneously or in sequence using the same lithography and etching processes, allowing the STO to automatically position itself relative to the main magnetic pole without requiring separate alignment steps. This self-alignment mechanism ensures consistent positional relationship while maintaining manufacturing feasibility
Solution Approach 2:
The formation processes for the STO and main magnetic pole are merged into a single integrated process flow. Both structures are patterned and etched using the same lithography mask and etching conditions, ensuring that their positional relationship is determined by the same manufacturing parameters. This merging of processes eliminates the need for separate alignment operations and reduces cumulative positioning errors
2Adaptability or versatility
If separate lithography and etching processes are used for the main magnetic pole and STO, then design flexibility is improved, but the positional alignment accuracy deteriorates due to cumulative manufacturing variations
Solution Approach 1:
The lithography pattern for both the main magnetic pole and STO is defined in advance using a single mask design that specifies their relative positions. The etching process is then performed to simultaneously create both structures according to this pre-defined pattern. This preliminary action ensures that the positional relationship is established before any manufacturing variations can accumulate
Solution Approach 2:
A common lithography mask serves as an intermediary that transfers the desired positional relationship between the main magnetic pole and STO onto the substrate. This mask acts as a reference frame that both structures must align to, ensuring consistent relative positioning. The mask pattern includes alignment features that guide the formation of both structures with precise spatial relationships
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach ensures a stable high frequency magnetic field assist effect, enhancing recording density and maintaining consistent performance by accurately determining the positional relationship between the main magnetic pole and the STO, thus overcoming positional misalignment issues.
Implementation Method 1
a spin torque oscillator disposed in the vicinity of the main magnetic pole
Implementation Method 2
The STO has a magnetic-film stacked structure similar to a read sensor such as GMR or TMR used in the head of a magnetic disk apparatus
Implementation Method 3
a main magnetic pole that generates a recording field
Implementation Method 4
The recording medium is irradiated with a high frequency magnetic field separately from the recording field to make the magnetization of the recording medium resonate and easier to move
Data Source
AI summary
To uniformly determine the positional relationship between a main magnetic pole and a spin torque oscillator while independently optimizing the main magnetic pole and the spin torque oscillator. On a trailing end surface of a main magnetic pole, a step is provided at the boundary between the main magnetic pole and a gap material disposed on both sides thereof, and a spin torque oscillator is formed on the step. The spin torque oscillator is effectively separated into two regions by utilizing the step. Further, a part of the spin torque oscillator is removed so as to disable the unwanted region, thereby realizing a self-alignment type high frequency magnetic field assisted magnetic recording head structure such that the positions of the end portions of the main magnetic pole and the spin torque oscillator are aligned.